1. Field of the Invention
The present invention generally relates to apparatus for sorting articles and in particular relates to an apparatus for sorting mushrooms or like articles which are generally symmetrical about an axis and are heavy at one end.
2. Description of the Prior Art
Presently, mushrooms are sorted manually either by those who pick the mushrooms or by workers at the packing where the mushrooms are packaged. Generally, the workers simply guess as to whether the mushroom falls in one of at least three size categories, large, medium, and small. It will be appreciated that it would be very advantageous to provide an apparatus for mechanically sorting the mushrooms, not only because mechanization would reduce labor costs, but also to eliminate the guess work in making the size classification.
However, mushrooms are relatively delicate and would be easily broken by conveying apparatus used for other produce and objects. That is to say, the mushrooms will break apart, for example, the caps will be broken from the stems of the mushrooms. Also, mushrooms cannot be handled in a moist environment because the mushrooms will decay and rot. Thus, a water handling system, such as used to handle delicate produce such as apples, cannot be employed in handling mushrooms. It is felt that none of the prior art conveying and sorting systems are adaptable to the sorting of mushrooms, and the present invention provides the first apparatus for mechanically sorting mushrooms according to size.
Air cushion conveyors are known in the prior art. In an American Society of Agricultural Engineers, Paper No. 77-1534, entitled "An Air Conveyor System For Fruits And Vegetables", an air conveyor system was described as consisting of a plenum and a slotted conveyor surface. In this paper, the conveyor surface was solid (that is, it was not perforated) and slots were formed in the rear end wall of the conveyor. Air is blown through this slot to convey the produce away from such slot.
The Randall U.S. Pat. No. 3,075,625 discloses an orienting apparatus for articles such as sliced food products which includes an inclined chute having a perforated bottom wall and vertical walls at the sides thereof which converge in the direction of the lower end of the chute. Air is blown upwardly through the perforated bottom wall, and as the air strikes the bottom of the article sliding down the chute, the air is deflected to the sides of the article and passes upwardly between the sides of the article and the converging side walls of the chute. This provides a cushioning effect which tends to center the article between the side walls.
In the fruit orienting mechanism of the Lorenzen U.S. Pat. No. 2,793,734, a conveyor includes a plurality of cups formed therein for receiving a single fruit in each cup. The cups include a conical wall force terminating at its upper end in a ring and at its lower end in an orifice. As shown in the drawings of this patent, the fruit (apple) is suspended in a stream of air flowing upwardly through the cup. Due to a drag force effect on a periphery of the fruit, the fruit rotates to a position such that its maximum diameter is in a plane essentially normal to the axial path of the air directed through the cup.
The Simmons U.S. Pat. No. 3,327,850, Moyer U.S. Pat. No. 3,955,678 and Stephanos U.S. 3,774,040 patents all deal with apparatus for grading articles according to size which utilize various photoelectric detectors and various control circuits associated with the detectors which cooperate to operate ejection apparatus to divert articles from a conveyor according to their size. It is also known that cameras are now available in the marketplace which incorporates a linear array of photo cells and circuitry to determine the size of an object moving past the camera. For example, the Reticon Corporation of Sunnyvale, Calif. manufactures an analog/digital line scan camera (Model LC64P) which can be thresholded to produce a digital output only when the article viewed by the camera is larger than a predetermined size.
The patents to Anderson U.S. Pat. No. 3,549,008, Simmons U.S. Pat. No. 3,327,850, Simmons U.S. Pat. No. 3,455,444, and Greenwood et al U.S. Pat. No. 3,770,111 disclose the combination of scanning means for measuring a physical characteristic with a selectively actuated air ejection system.